> "Def[ies] the known laws of physics", is a good sign your imagination is too narrow, or your understanding of physics too small.
I don't know but I would assume they are usually referring to conservation of momentum being violated, rather than something like the 2nd law of thermodynamics or the Heisenberg uncertainty principle. Which is pretty easy to see unless you have reason to believe there is something rather crazy happening that you cannot see (like I imagine a neutron being emitted at >99% of the speed of light to cancel some change in momentum that you otherwise can't explain).
I don't know but I would assume they are usually referring to conservation of momentum being violated, rather than something like the 2nd law of thermodynamics or the Heisenberg uncertainty principle. Which is pretty easy to see unless you have reason to believe there is something rather crazy happening that you cannot see (like I imagine a neutron being emitted at >99% of the speed of light to cancel some change in momentum that you otherwise can't explain).